Cylinder heads for internal combustion engines



L. PERAS Sept. 27, 1966 CYLINDER HEADS FOR INTERNAL COMBUSTION ENGINES Filed March 50, 1964 United States Patent M 3,274,981 CYLINDER HEADS FOR INTERNAL COMBUSTION ENGINES Lucien Pras, Billancourt, France, assignor to Regie Nationale des Usines Renault, Billancourt, France, a French works Filed Mar. 30, 1964, Ser. No. 355,730 Claims priority, application France, Apr. 8, 1963, 930,834, Patent 1,361,447 Claims. (Cl. 12330) This invention relates to cylinder heads for internal combustion engines having at least two in-line cylinders, in which cylinder heads it is already known to provide inlet passages of special shape to impart a swirling motion about the cylinder axis to the gas mixture sucked in.

This has become an indispensable feature in certain types of engines in which the fuel is injected directly into the combustion chamber.

More specifically, it is known to so devise the shape and direction of the inlet passages to cause the gas stream guided by the passage walls to be conveyed to the valve after being constrained to assume the form of motion best suited to the required swirl effect.

It is also known that the rate of swirl obtainable in the cylinder is all the greater as the degree of eccentricity of the inlet duct routing with respect to the valve axis is greater. However, if an inlet passage is to be provided for each valve in the customary way, the maximum eccentricity which can be imparted to it is strictly limited by the need for correctly locating the cylinder head securing studs and the passageways for the pushrods, it being understood that there can be no question of increasing the centre distance between the cylinders in order to facilitate the routing of these passages.

The present invention contemplates a new routing for such inlet passages, whereby they may be given, within the limits of space available, the eccentricity required to ensure maximum swirl.

Essentially, a cylinder head according to the present invention is characterized in that, in respect to each set of two adjacent cylinders, the inlet valve seats are positioned on either side of the exhaust valve seats, in alignment with the cylinders, while the corresponding inlet passages have a common inlet port substantially equidistant from the inlet valve seats, from which port each passage follows a path which is slightly oblique with respect to the alignment of said cylinders and terminates in a volute which leads up to the corresponding inlet valve by skirting the same externally with respect to the cylinder.

The description which follows of a form of embodiment of a cylinder head according to the invention, given with reference to the accompanying non-limitative exemplary drawing, will give a clear understanding of how the invention can be carried into practice.

In the drawing,

FIGURE 1 is a fragmental sectional view of the cylinder head, taken through the line II of FIGURE 2; and

FIGURES 2 and 3 are sectional views of said cylinder head, taken respectively through the lines IIII and IIIIII of FIGURE 1.

Reference to FIGURE 1 shows a plan view of the routing of the inlet passages 1 and 2 of two adjacent cylinders designated by reference numerals 3 and 4.

The inlet valve seat of cylinder 3 is denoted by numeral 5 and that of cylinder 4 by numeral 6, these seats being positioned on either side of the exhaust valve seats 7 and 8.

The inlet passages 1 and 2 have a common inlet port 9 which is positioned as far as possible equidistantly from the axes of the two cylinders and opens out on the side of the cylinder head, between the exhaust tappet pushrod 3,274,981 Patented Sept. 27, 1966 passageways 10 (not shown). Preferably, in order to impart maximum width to said inlet port, said passageways consist of tubes extending therethrough. To that end also, the centre distance between said tubes may be chosen greater than the centre distance between exhaust valve seats 7 and 8, as is the case in the specific example herein considered.

Extending from inlet port 9, each inlet passageway 1 and 2 follows a slightly oblique path with respect to the cylinder alignment, then sweeps inwardly up to the corresponding inlet valve seat along a volute path which skirts the same, as shown in the drawing.

It will be noted that said passages are shown to have, at the mouth of the volute, with respect to the inlet valve seats, an eccentricity e which is a least equal to the valve radius R (see FIGURE 3) having regard for the fact that a lesser degree of eccentricity would not permit of obtaining a stable swirling motion of the gas stream to be admitted into the cylinder.

From the inlet port 9 to the valves, said inlet passages have a gradually decreasing rectangular cross-section (see FIGURES 2 and 3) which produces the effect of a convergent section, i.e. speeds up the mass of gas to be admitted into the cylinder. In addition, each inlet passage slopes downwardly towards the valve seat, whereby the combustion mixture has imparted to it a direction favourable to direct penetration into the cylinder (there being no swirl chamber provided). In order to obtain as uniform a gyratory velocity of the gas stream as possible, it will be of advantage to make the width of said inlet passages markedly smaller than their height (for practical purposes, the width must not exceed two-thirds of the height).

Reference to the drawing clearly shows that the section of the inlet passages is devoid of constrictions or sudden changes in direction, thereby enabling said passages to supply the cylinders with a minimum loss of pressure, the direction of penetration of the gas stream into the cylinders being shown by the arrows in FIGURES l and 2. Further, as is most clearly shown in FIGURE 1, the maximum dimension of the volute is located on the side remote from the exhaust valve seats 7 and 8, thus readily enabling the water cooling circuit to pass between the inlet and exhaust valve seats, the exhaust manifold combining into a single passage 11.

Reference numeral 12 designates the holes for the cylinder head fixing studs.

Although one embodiment of the invention has been described and illustrated, it will be obvious to those skilled in the art that various changes, substitutions of elements and arrangements of parts may be made without departing from the spirit and scope of the invention as it is hereinafter defined in the appended claims.

I claim:

1. A cylinder head for internal combustion engines having at least two in-line cylinders, said head comprising an inlet and exhaust valve seat associated with each cylinder, the inlet seats of adjacent cylinders being positioned on either side of their corresponding outlet seats, a common inlet port for the inlet seats of adjacent cylinders, an inlet passage connecting said inlet port with its c-orre sponding inlet seats, each of said inlet passages being routed slightly obliquely with respect to a line passing through the central longitudinal axes of said cylinders and terminating in a volute which leads up to and skirts the corresponding inlet valve seat before passing into said cylinder, the inner vertical wall of said inlet passage at the mouth of said volute being spaced at least as great a distance from the central longitudinal axis of said inlet seat as the inner annular wall of said inlet seat.

2. The cylinder head of claim 1 wherein said inlet port 3 is positioned substantially equidistantly from the respective inlet valve seats.

3. A cylinder head as claimed in claim 1, wherein each inlet passage slopes downwardly towards the corresponding inlet valve seat.

4. A cylinder head as claimed in claim 1, wherein each inlet passage has a cross-section which is narrower than it is high and which decreases towards the corresponding inlet valve seat.

5. A cylinder head as claimed in claim 1 further comprising an exhaust conduit extending from each cylinder and a common exhaust port into which the respective exhaust conduits from a pair of adjacent cylinders lead.

2,219,241 10/1940 Tebaldi. 3,159,148 12/1964 Nallinger et al. l23--188 FOREIGN PATENTS 9/1956 France. 4/1959 France.

10 MARK NEWMAN, Primary Examiner.

RICHARD B. WILKINSON, Examiner.

L. M. GOODRIDGE, Assistant Examiner. 

1. A CYLINDER HEAD FOR INTERNAL COMBUSTION ENGINES HAVING AT LEAST TWO IN-LINE CYLINDERS, SAID HEAD COMPRISING AN INLET AND EXHAUST VALVE SEAT ASSOCIATED WITH EACH CYLINDER, THE INLET SEATS OF ADJACENT CYLINDERS BEING POSITIONED ON EITHER SIDE OF THEIR CORRESPONDING OUTLET SEATS, A COMMON INLET PORT FOR THE INLET SEATS OF ADJACENT CYLINDERS, AN INLET PASSAGE CONNECTING SAID INLET PORT WITH ITS CORRESPONDING INLET SEATS, EACH OF SAID INLET PASSAGES BEING ROUTED SLIGHTLY OBLIQUELY WITH RESPECT TO A LINE PASSING THROUGH THE CENTRAL LONGITUDINAL AXES OF SAID CYLINDERS AND TERMINATING IN A VOLUTE WHICH LEADS UP TO SKIRTS THE CORRESPONDING INLET VALVE SEAT BEFORE PASSING INTO SAID CYLINDER, THE INNER VERTICAL WALL OF SAID INLET PASSAGE AT THE MOUTH OF SAID VOLUTE BEING SPACED AT LEAST AS GREAT A DISTANCE FROM THE CENTRAL LONGITUDINAL AXIS OF SAID INLET SEAT AS THE INNER ANNULAR WALL OF SAID INLET SEAT. 